Sampling culturable heterotrophs from microcosms: a statistical analysis.

The contributions of different sources of error in sampling mixed and unmixed bacterial microcosms were evaluated by using analysis of variance. Culturable heterotrophic bacteria from a turbid freshwater impoundment were sampled from 9-liter tanks that were unagitated or mixed with magnetic stirrers or pumps and from dilution bottles that were unagitated or agitated with a mechanical shaker. Axenic cultures of Enterobacter aerogenes were also sampled from manually shaken test tubes. In both agitated and unagitated tanks and in unagitated dilution bottles, dilutions made from the same sampling pipette were significantly different, showing a clumping of bacteria on the scale of millimeters. Also, microcosms within a single experiment differed from one another by a large margin. Dilution mean squares and tank or bottle mean squares were homogeneous for all types of tanks and unagitated bottles, indicating that the gentle mixing provided by pumps and stir bars did not reduce either millimeter scale or intermicrocosm variability over what prevailed in unagitated microcosms. By contrast, the vigorously shaken bottles and test tubes showed no millimeter scale variability. Intermicrocosm variability was undetectable in test tubes and two orders of magnitude less in shaken bottles than in unshaken bottles. When these facts are coupled with the inherent statistical advantage of replicating large rather than small experimental units, it is concluded that sampling error in the enumeration of aquatic bacteria in microcosms will be reduced by using numerous, small, violently agitated microcosms with a minimum of subsampling per microcosm.     

Divergent views of hospital staff on detecting and managing hypertension.

A questionnaire about detecting and managing hypertension was answered by 76 out of 110 (69%) doctors and 116 out of 195 (63%) qualified nurses in a large hospital. There was no general agreement on the method of taking diastolic blood pressures or on the level of hypertension requiring treatment. Most of the clinicians treated mild hypertension, although no proof exists that such treatment is beneficial. Almost everyone questioned agreed that measuring blood pressure in all patients attending hospital is important. Agreement should be reached, however, on which phase of diastolic blood pressure should be used.     

Substance P and acetylcholine are co-localized in the pathway mediating mucociliary activity in Rana pipiens

Mucociliary activity is an important clearance mechanism in the respiratory system of air breathing vertebrates. Substance P (SP) and acetylcholine play a key role in the stimulation of the mucociliary transport in the frog palate. In this study, retrograde neuronal tracing was combined with immunocytochemistry for SP and choline acetyl transferase (ChAT) in the trigeminal ganglion and for neurokinin-1 receptor (NK1R) in the palate of Rana pipiens. The cells of origin of the palatine nerve were identified in the trigeminal ganglion using the retrograde tracer Fluorogold (FG). Optimal labeling of FG cells in the trigeminal ganglion was obtained at 96 h of exposure. Immunoflorescent shows that SP and acetylcholine are co-localized in 92% of the cells labeled with FG in the trigeminal ganglion. NK1 receptors were found in the membrane of epithelial and goblet cells of the palate. Ultrastructural study of the palate showed axonal-like endings with vesicles in connection with epithelial and goblet cells. These results further support the concerted action of both neurotransmitters in the regulation of mucociliary activity in the frog palate.     

RHODOLITHS: BETWEEN ROCKS AND SOFT PLACES

Rhodoliths (maërl) are widely distributed in the worlds' oceans and have an excellent fossil record. Individuals are slow growing, may be long lived (>100 years), and are resilient to a variety of environmental disturbances. Their external morphology and internal growth bands are potential archives of environmental variation at scales of within years to tens of years. At high densities, these free-living non-geniculate coralline algae form rhodolith beds, communities of high diversity that can be severely impacted by resource extraction.